U.S. patent application number 13/667592 was filed with the patent office on 2014-05-08 for translating between testing requirements at different reference points.
This patent application is currently assigned to ALCATEL-LUCENT USA INC.. The applicant listed for this patent is ALCATEL-LUCENT USA INC.. Invention is credited to Teck Hu.
Application Number | 20140128006 13/667592 |
Document ID | / |
Family ID | 49552460 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140128006 |
Kind Code |
A1 |
Hu; Teck |
May 8, 2014 |
TRANSLATING BETWEEN TESTING REQUIREMENTS AT DIFFERENT REFERENCE
POINTS
Abstract
Embodiments of the claimed subject matter provide a method and
apparatus for translating testing requirements between different
reference points. Some embodiments of the method include generating
mapping information that relates at least one first requirement
associated with an active antenna array to at least one second
requirement associated with the active antenna array. The first
requirements are associated with a first reference point and the
second requirements are associated with a second reference point
that differs from the first reference point. Some embodiments of
the method also include storing the mapping information in a
non-transitory computer-readable storage media.
Inventors: |
Hu; Teck; (Melbourne,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALCATEL-LUCENT USA INC. |
Murray Hill |
NJ |
US |
|
|
Assignee: |
ALCATEL-LUCENT USA INC.
Murray Hill
NJ
|
Family ID: |
49552460 |
Appl. No.: |
13/667592 |
Filed: |
November 2, 2012 |
Current U.S.
Class: |
455/73 |
Current CPC
Class: |
H04B 17/15 20150115;
H04B 17/104 20150115 |
Class at
Publication: |
455/73 |
International
Class: |
H04B 1/38 20060101
H04B001/38 |
Claims
1. A method, comprising: generating mapping information that
relates at least one first requirement associated with an active
antenna array to at least one second requirement associated with
the active antenna array, wherein said at least one first
requirement is associated with a first reference point and said at
least one second requirement is associated with a second reference
point that differs from the first reference point; and storing said
mapping information in a non-transitory computer-readable storage
media.
2. The method of claim 1, wherein said at least one first
requirement comprises a first threshold value of an adjacent
channel leakage ratio associated with an antenna connection point
between baseband circuitry and the active antenna array.
3. The method of claim 2, wherein said at least one second
requirement comprises a second threshold value of the adjacent
channel leakage ratio associated with a far-field reference
point.
4. The method of claim 2, wherein said at least one second
requirement comprises a plurality of second threshold values of the
adjacent channel leakage ratio associated with a plurality of
far-field reference points associated with different
angles-of-arrival at the active antenna array.
5. The method of claim 1, wherein generating the mapping
information comprises generating the mapping information based on a
correlation parameter associated with the active antenna array and
at least one predetermined value of at least one of the first
requirement or the second requirement.
6. The method of claim 5, wherein the correlation parameter varies
from a value of 1.0 when antenna elements in the active antenna
array are fully correlated and a value of 0 when antenna elements
in the active antenna array are uncorrelated.
7. The method of claim 1, comprising translating at least one
measured value of at least one requirement using the mapping table,
wherein said at least one measured value is measured at one of the
first and second reference points and the translated value of said
at least one measured value corresponds to the other one of the
first and second reference points.
8. A method, comprising: accessing information indicating at least
one first requirement associated with an active antenna array, said
at least one first requirement being associated with a first
reference point; determining at least one second requirement
associated with the active antenna array based on measurements
performed at a second reference point different than the first
reference point; and translating said at least one second
requirement to correspond to at least one value associated with the
first reference point, wherein said translation is performed using
mapping information that relates requirements associated with the
first reference point and requirements associated with the second
reference point.
9. The method of claim 8, wherein said at least one first
requirement comprises a first threshold value of an adjacent
channel leakage ratio applied at an antenna connection point
between baseband circuitry and the active antenna array.
10. The method of claim 9, wherein said at least one second
requirement comprises a value of the adjacent channel leakage ratio
determined based on measurements performed at a far-field reference
point.
11. The method of claim 9, wherein said at least one second
requirement comprises a plurality of values of the adjacent channel
leakage ratio determined based on measurements performed at a
plurality of far-field reference points associated with different
angles-of-arrival at the active antenna array.
12. The method of claim 8, wherein the mapping information is
generated based on a correlation parameter associated with the
active antenna array and at least one predetermined value of at
least one of the first requirement or the second requirement.
13. The method of claim 12, wherein the correlation parameter
varies from a value of 1.0 when antenna elements in the active
antenna array are fully correlated and a value of 0 when antenna
elements in the active antenna array are uncorrelated.
14. The method of claim 8, comprising comparing the translated
values of said at least one second requirement to values of said at
least one first requirement.
15. An apparatus, comprising: a translator configurable to: access
information indicating at least one first requirement associated
with an active antenna array, said at least one first requirement
being associated with a first reference point; access information
indicating at least one second requirement associated with the
active antenna array, wherein said at least one second requirement
is determined based on measurements performed at a second reference
point different than the first reference point; and translate said
at least one second requirement to correspond to at least one value
associated with the first reference point, wherein said translation
is performed using mapping information that relates requirements
associated with the first reference point and requirements
associated with the second reference point.
16. The apparatus of claim 15, wherein said at least one first
requirement comprises a first threshold value of an adjacent
channel leakage ratio applied at an antenna connection point
between baseband circuitry and the active antenna array.
17. The apparatus of claim 16, wherein said at least one second
requirement comprises a value of the adjacent channel leakage ratio
determined based on measurements performed at a far-field reference
point.
18. The apparatus of claim 16, wherein said at least one second
requirement comprises a plurality of values of the adjacent channel
leakage ratio determined based on measurements performed at a
plurality of far-field reference points associated with different
angles-of-arrival at the active antenna array.
19. The apparatus of claim 15, comprising a reference point mapping
table configurable to store mapping information is generated based
on a correlation parameter associated with the active antenna array
and at least one predetermined value of at least one of the first
requirement or the second requirement, and wherein the translator
is configurable to access the mapping information stored in the
reference point mapping table.
20. The apparatus of claim 19, wherein the correlation parameter
varies from a value of 1.0 when antenna elements in the active
antenna array are fully correlated and a value of 0 when antenna
elements in the active antenna array are uncorrelated.
21. The apparatus of claim 15, comprising a comparator configurable
to compare the translated values of said at least one second
requirement to values of said at least one first requirement.
Description
BACKGROUND
[0001] This application relates generally to communication systems,
and, more particularly, to wireless communication systems.
[0002] Conventional wireless communication systems provide wireless
connectivity to user equipment using devices such as base stations,
access points, e-nodeBs, and the like. The base stations are
typically connected to one or more antennas for transmitting and
receiving radiofrequency signals. For example, some conventional
wireless communication systems deploy antenna arrays that include
arrays of antenna elements for transmitting and receiving signals.
The passive antenna arrays used for uplink and downlink
transmissions in legacy wireless communication systems can include
multiple dipoles or other antenna elements that are driven by a
single transceiver. Radiation from the multiple elements in a
passive antenna array is therefore fully correlated.
[0003] Wireless communication equipment is designed to satisfy
various requirements. One exemplary requirement includes an upper
limit on the adjacent channel leakage ratio (ACLR) that is set by
the requirement that leakage from one wireless communication
channel should not reduce the capacity or throughput on another
wireless communication channel by more than 5%. Compliance testing
of equipment may be performed before the equipment is sold or
deployed in the field to ensure that the wireless communication
equipment satisfies the requirements. Equipment vendors and service
providers may use the results of compliance testing to compare,
select, purchase, configure, or deploy wireless communication
equipment in the field. Compliance testing of passive antenna
arrays can be performed by determining whether the test
requirements are met at a reference point, such as a reference
point at an antenna connection point or using far-field
measurements at a distant reference point. For example, compliance
testing at the antenna connection or in the far-field may be used
to determine whether the transmitter satisfies a 45 dBc limit on
the ACLR. The same requirements, such as the ACLR, can be applied
at either the antenna connection point or the far-field point.
SUMMARY OF EMBODIMENTS
[0004] The following presents a simplified summary of the disclosed
subject matter in order to provide a basic understanding of some
aspects of the disclosed subject matter. This summary is not an
exhaustive overview of the disclosed subject matter. It is not
intended to identify key or critical elements of the disclosed
subject matter or to delineate the scope of the disclosed subject
matter. Its sole purpose is to present some concepts in a
simplified form as a prelude to the more detailed description that
is discussed later.
[0005] Active antenna arrays differ from passive antenna arrays at
least in part because active antenna arrays use a different
transceiver to drive each antenna element in the active antenna
array. Radiation from the different antenna elements may therefore
range from completely correlated to completely uncorrelated
depending on the transmission parameters used by the different
transceivers. Consequently, the same transmitter requirements
cannot be applied at different reference points such as the antenna
connection point and the distant reference point used for far-field
measurements. For example, the innumerable number of possible
implementations of the various beamforming weights, digital
processing, and signal distributions applied to the antenna arrays
in different deployment scenarios makes the far field requirement
more complex than the requirement that can be applied at the
antenna connection.
[0006] This presents a problem for equipment manufacturers and
providers who would like to implement a standard approach to
compliance testing that facilitates the comparison of different
products produced by different equipment manufacturers. For
example, some transmitters may be constructed using baseband
circuitry that is separate from the antenna array. In that case,
compliance requirements can easily be applied at the antenna
connection point by sampling the signal provided by the baseband
circuitry as it travels to the antenna array. However, other
transmitters deploy the baseband circuitry and the antenna array in
a single enclosed package and are not amenable to testing by
sampling signals at the antenna connection point. These products
are more amenable to far-field testing using a distant reference
point. The disclosed subject matter is directed to addressing the
effects of one or more of the problems set forth above.
[0007] In one embodiment, a method is provided for supporting the
translation of testing requirements between different reference
points. Some embodiments of the method include generating mapping
information that relates at least one first requirement associated
with an active antenna array to at least one second requirement
associated with the active antenna array. The first requirements
are associated with a first reference point and the second
requirements are associated with a second reference point that
differs from the first reference point. Some embodiments of the
method also include storing the mapping information in a
non-transitory computer-readable storage media.
[0008] In another embodiment, a method is provided for translating
testing requirements between different reference points. Some
embodiments of the method include accessing information indicating
one or more first requirements associated with an active antenna
array. The first requirements are associated with a first reference
point. Some embodiments of the method also include determining one
or more second requirements associated with the active antenna
array based on measurements performed at a second reference point
different than the first reference point. Some embodiments of the
method also include translating the second requirements to
correspond to one or more values associated with the first
reference point. The translation is performed using mapping
information that relates requirements associated with the first
reference point and requirements associated with the second
reference point.
[0009] In yet another embodiment, an apparatus is provided for
translating testing requirements between reference points. Some
embodiments of the apparatus include a translator configurable to
access information indicating one or more first requirements
associated with an active antenna array. The first requirements are
associated with a first reference point. Some embodiments of the
translator are also configurable to access information indicating
one or more second requirements associated with the active antenna
array. The second requirements are determined based on measurements
performed at a second reference point different than the first
reference point. Some embodiments of the translator are further
configurable to translate the second requirements to correspond to
one or more values associated with the first reference point. The
translation is performed using mapping information that relates
requirements associated with the first reference point and
requirements associated with the second reference point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The disclosed subject matter may be understood by reference
to the following description taken in conjunction with the
accompanying drawings, in which like reference numerals identify
like elements, and in which:
[0011] FIG. 1 conceptually illustrates one exemplary embodiment of
a wireless communication system;
[0012] FIG. 2 conceptually illustrates one exemplary embodiment of
a transceiver device that may be coupled to active antenna
array;
[0013] FIG. 3A conceptually illustrates a first exemplary
embodiment of a testing apparatus that can be used to perform
far-field testing of a transceiver device;
[0014] FIG. 3B conceptually illustrates a second exemplary
embodiment of a testing apparatus that can be used to perform
far-field testing of a transceiver device;
[0015] FIG. 4 conceptually illustrates one exemplary embodiment of
a compliance tester; and
[0016] FIG. 5 conceptually illustrates one exemplary embodiment of
a method for translating test requirements for active antenna
arrays between different reference points.
[0017] While the disclosed subject matter is susceptible to various
modifications and alternative forms, specific embodiments thereof
have been shown by way of example in the drawings and are herein
described in detail. It should be understood, however, that the
description herein of specific embodiments is not intended to limit
the disclosed subject matter to the particular forms disclosed, but
on the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the scope of the
appended claims.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0018] Illustrative embodiments are described below. In the
interest of clarity, not all features of an actual implementation
are described in this specification. It will of course be
appreciated that in the development of any such actual embodiment,
numerous implementation-specific decisions should be made to
achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure. The description and drawings merely illustrate the
principles of the claimed subject matter. It should thus be
appreciated that those skilled in the art may be able to devise
various arrangements that, although not explicitly described or
shown herein, embody the principles described herein and may be
included within the scope of the claimed subject matter.
Furthermore, all examples recited herein are principally intended
to be for pedagogical purposes to aid the reader in understanding
the principles of the claimed subject matter and the concepts
contributed by the inventor(s) to furthering the art, and are to be
construed as being without limitation to such specifically recited
examples and conditions.
[0019] The disclosed subject matter is described with reference to
the attached figures. Various structures, systems and devices are
schematically depicted in the drawings for purposes of explanation
only and so as to not obscure the description with details that are
well known to those skilled in the art. Nevertheless, the attached
drawings are included to describe and explain illustrative examples
of the disclosed subject matter. The words and phrases used herein
should be understood and interpreted to have a meaning consistent
with the understanding of those words and phrases by those skilled
in the relevant art. No special definition of a term or phrase,
i.e., a definition that is different from the ordinary and
customary meaning as understood by those skilled in the art, is
intended to be implied by consistent usage of the term or phrase
herein. To the extent that a term or phrase is intended to have a
special meaning, i.e., a meaning other than that understood by
skilled artisans, such a special definition is expressly set forth
in the specification in a definitional manner that directly and
unequivocally provides the special definition for the term or
phrase. Additionally, the term, "or," as used herein, refers to a
non-exclusive "or," unless otherwise indicated (e.g., "or else" or
"or in the alternative"). Also, the various embodiments described
herein are not necessarily mutually exclusive, as some embodiments
can be combined with one or more other embodiments to form new
embodiments.
[0020] As discussed herein, transceiver systems including base
stations and active antenna arrays may not be amenable to testing
at the same reference points. For example, some transmitters may be
constructed using baseband circuitry that is separate from the
antenna array. In that case, compliance requirements can be applied
at the antenna connection point. However, other transmitters deploy
the baseband circuitry and the antenna array in a single enclosed
package and consequently testing these transmitters at the antenna
connection point may require opening or destroying the package.
Far-field testing at a distant reference point may therefore be
preferable.
[0021] At least in part to provide the flexibility to perform
compliance testing at different reference points, the present
application describes embodiments of techniques for supporting the
translation of testing requirements between different reference
points. In some embodiments, a mapping may be defined so that the
mapping may be used to translate between far-field requirements at
a distant reference point and antenna connection requirements
applied at an antenna connection point between baseband circuitry
and the plurality of antenna elements. For example, correlation
parameters for the antenna elements in the active antenna array may
be used to relate far-field requirements to antenna connection
requirements such as a first antenna connection requirement for the
plurality of antenna elements and a second antenna connection
requirement for one antenna element. The correlation parameter
varies from a value of 1.0 when the antenna elements are fully
correlated to a value of zero when the antenna elements are
uncorrelated. The results of compliance testing of different
transmitters can then be compared by converting between results of
far-field measurements performed at the distant reference point for
one set of transmitters and antenna connection point measurements
performed for another set of transmitters.
[0022] FIG. 1 conceptually illustrates one exemplary embodiment of
a wireless communication system 100. In the illustrated embodiment,
the wireless communication system 100 includes base stations 105
that are used to generate baseband signals that are provided to
active antenna arrays 110. As used herein, the term "base station"
should be understood to encompass devices including circuitry for
generating baseband signals, base stations, base station routers,
access point, e-nodeBs, home base station routers, femtocells, and
the like. The base stations 105 may be used to provide wireless
connectivity to user equipment 115. For example, the active antenna
array 110(1) associated with the base station 105(1) may perform
beamforming to transmit a beam 120(1) towards the user equipment
115 to support communication over one or more channels. The energy
received by the user equipment 115 in the channels supported by the
beam 120(1) may be referred to as the "wanted" energy. However, the
base stations 105 may also provide "unwanted" interfering signals
to the user equipment 115. For example, energy transmitted from the
active antenna array 110(2) in the beam 120(2) on other channels
may leak into the channels supported by the beam 120(1) and
interfere with communication between the base station 105(1) and
the user equipment 115.
[0023] The base stations 105 or the active antenna arrays 110 may
be characterized by various requirements. For example, the active
antenna arrays 110 may be characterized by an adjacent channel
leakage power ratio (ACLR) that is defined as the ratio of the mean
power centered on an assigned channel frequency to the mean power
centered on an adjacent channel frequency. For base stations 105
that include active antenna arrays 110, the ACLR requirement can be
applied or tested at different reference points including, but not
limited to, output nodes of individual transceivers (not shown in
FIG. 1) coupled to elements of the active antenna arrays 110, an
output node of a Radio Distribution Network (not shown in FIG. 1)
coupled to elements of the active antenna arrays 110, or far-field
reference points that are far enough from the active antenna array
110 to sample the far field signal generated by the active antenna
array 110. The ACLR may have a spatial characteristic such that
values of the ACLR determined by measuring characteristics of
signals received at the different reference points may differ from
each other at least in part due to beamforming properties and use
of multiple transceivers of the active antenna array 110.
[0024] Establishing requirements for compliance testing at a single
reference point, e.g. at the antenna connection(s) of the
transceivers, has the benefit of simplicity and ease of
implementation. However, compliance testing at the antenna
connection point also poses practical challenges for
implementations of the base stations 105 and the active antenna
arrays 110 in which access to antenna connection(s) is difficult or
infeasible. Conversely, compliance testing of the base stations 105
and the active antenna arrays 110 in the far-field region requires
very large physical structures because the far-field region may
extend to 100 meters or more from the active antenna arrays 110. In
the illustrated embodiment, a default reference point may therefore
be defined and then relationships for translating between
requirements at the default reference point and other reference
points may be established and used for compliance testing. The
default reference points are selected in some embodiments based on
the criteria that the default reference point satisfies a majority
of the radiofrequency requirements that need to be redefined for
active antenna arrays (relative to passive antenna arrays). An
alternative reference point may be defined for requirements that
have spatial characteristics that can or should be captured with
far field requirements.
[0025] The default reference requirement and any additional
reference requirements should result in the same compliance
performance, e.g. the two requirements should be defined so that
they can be mapped to each other. The innumerable number of
possible implementations of the various beamforming weights,
digital processing, and signal distributions that may be used to
configure or operate the antenna arrays in different deployment
scenarios makes the far field requirement more complex. Some
embodiments of the compliance testing described herein may
therefore define the mapping between the different reference points
on the basis of correlations between the signals transmitted by the
different elements in the active antenna arrays 110. The parameters
and procedures that define a mapping can be declared as part of the
test procedure. In one embodiment, testing requirements for the
base stations 105 or active antenna arrays 110 may be established
by requiring that the capacity or throughput loss of the victim
system shall not exceed 5%. For example, the spatial impacts of the
active antenna arrays 110 may be modelled by taking the 95%
cumulative distribution function (CDF) of the ACLR value that is
obtained over various implementations of the wireless communication
system 100.
[0026] FIG. 2 conceptually illustrates one exemplary embodiment of
a transceiver device 200 that may be coupled to an active antenna
array. In the illustrated embodiment, the transceiver device 200
includes baseband circuitry 205 that is used to generate baseband
signals for transmission over the air interface. The baseband
circuitry 205 may be implemented in a base station. The baseband
circuitry 205 provides baseband signals to transceivers 210 that
are part of a transceiver array 215 that includes K transceivers
210 associated with L elements of an active antenna array. In the
illustrated embodiment, the transceivers 210 are coupled to a radio
distribution network 215. However, alternative embodiments of the
transceiver device 200 may not include a radio distribution network
215. The radio distribution network 215, if present, performs the
distribution of the TX outputs from the transceivers 210 into the
corresponding antenna paths and antenna elements, and a
distribution of RX inputs from antenna paths in the reverse
direction to the transceivers 210. For example, the radio
distribution network 215 may be used to map the K radiofrequency
input signals to the L antenna elements. The radio distribution
network 215 may therefore support connection of one transceiver to
1, 2, or all L antenna elements.
[0027] Compliance testing may be performed at the nodes 220 between
the transceivers 210 and the radio distribution network 215.
Testing at the nodes 220 corresponds to the conventional compliance
testing reference point for a passive antenna array. In the
illustrated embodiment, compliance testing is performed at the node
225, which may be referred to as the antenna connection point
because the elements of the active antenna array can be coupled to
the radio distribution network 215 at the node 225. During
compliance testing of the transceiver device 200, an antenna
connection tester 230 may be physically, electromagnetically, or
communicatively coupled to the node 225 (as shown in FIG. 2) to
sample signals that are conveyed between the radio distribution
network 215 and the active antenna array. Some embodiments of the
antenna connection tester 230 can perform measurements that are
used to derive values of testing requirements (such as the ACLR).
As discussed herein, the derived values of the testing requirements
at the antenna connection node 225 may be converted or translated
into values representative of the testing requirements at other
reference points.
[0028] FIG. 3A conceptually illustrates a first exemplary
embodiment of a testing apparatus 300 that can be used to perform
far-field testing of a transceiver device 305. In the illustrated
embodiment, the transceiver device 305 includes a radio
distribution network 310 that distributes a signal received at the
node 315 to antenna elements 320 (in the interest of clarity only
one indicated by a reference numeral) and an active antenna array
325. The testing apparatus also includes an anechoic chamber 330
that is designed to stop reflections of electromagnetic waves. For
example, the anechoic chamber 330 may be designed to reduce or stop
reflections of electromagnetic waves in a frequency band
corresponding to frequencies used to transmit or receive signals at
the active antenna array 325. Techniques for implementing anechoic
chambers 330 are known in the art and in the interest of clarity
are not discussed further herein.
[0029] A far-field reference point 335 may be defined in the
anechoic chamber 330 at a distance that is sufficiently far from
the transceiver device 305 to measure the far-field electromagnetic
field created by the active antenna array 325. Techniques for
selecting a distance sufficiently far from the source to sample the
far-field behavior of the active antenna array 325 (e.g., based
upon the wavelength or the diffraction behavior of the radiation)
are known in the art. During compliance testing of the transceiver
device 305, a far-field tester 340 can be deployed at the reference
point 335 or can be coupled to one or more sensors deployed at the
reference point 335 to sample signals transmitted by the active
antenna array 325. Some embodiments of the far-field tester 340 can
perform measurements that are used to derive values of testing
requirements (such as the ACLR). As discussed herein, the derived
values of the testing requirements at the far-field reference point
335 may be converted or translated into values representative of
the testing requirements at other reference points, such as the
antenna connection reference point 225 shown in FIG. 2.
[0030] FIG. 3B conceptually illustrates a second exemplary
embodiment of a testing apparatus 350 that can be used to perform
far-field testing of a transceiver device 305. The second exemplary
embodiment of the testing apparatus 350 differs from the first
exemplary embodiment of the testing apparatus 300 because the
far-field tester 355 is configurable to sense the far-field
radiation pattern generated by the transceiver device 305 at a
plurality of different locations within the anechoic chamber 330.
Some embodiments of the far-field tester 355 may be configured to
sense the far-field radiation pattern at locations that have
different angles-of-arrival with respect to the transceiver device
305. However, other embodiments of the far-field tester 350 may be
configured to sense the far-field radiation pattern at other
locations within the anechoic chamber 330. Some embodiments of the
far-field tester 355 can perform measurements that are used to
derive values of testing requirements (such as the ACLR) that
correspond to the different measurement locations. As discussed
herein, the derived values of the testing requirements at the
different measurement locations may be converted or translated into
values representative of the testing requirements at other
reference points, such as the antenna connection reference points
220, 225 shown in FIG. 2.
[0031] Some embodiments of the transceiver devices 305 may generate
a maximum power that is approximately equal to the sum of the
powers transmitted by the individual antenna elements 320 of the
active antenna array 325. The maximum power is equivalent to the
transmitted power when all the signals add coherently in the main
beam generated by the active antenna array 325, e.g. the beam
120(1) shown in FIG. 1. The level of unwanted signals used to
estimate the ACLR may be calculated by assuming or estimating
different levels of correlations between signals transmitted by the
individual antenna elements 320. For example, simulation studies
have demonstrated that fully correlated unwanted emission from the
antenna elements 320 corresponds to the worst case absolute
unwanted emissions. However, the correlation values of the
different antenna elements 320 may be difficult to model and thus
values in a range from 0 to 1.0 may be used. Some embodiments may
assume the worst case value of 1.0 when calculating the ACLR for
the transceiver device 305. This approach provides for a
requirement that ensures the worst case coexistence or a
requirement that is valid and not dependent on deployed system
correlation parameter.
[0032] Translating between the testing requirements at different
reference points may allow testing requirements to be defined at a
single reference point and then compared to tests performed at
other reference points. Some embodiments of the testing apparatuses
340, 350 may therefore define the testing requirements at the
antenna connection point. These definitions of the testing
requirements may be consistent with the conducted measurements
approach as provided in the FCC guidance, namely the
Measure-and-Sum approach. Embodiments of these testing requirements
may also be consistent with the fully correlated unwanted emissions
where the antenna connection point requirement would be identical
to the far field over-the-air requirement for testing requirements
such as ACLR. For example, an ACLR of 45 dBc at the antenna
connection point may be used as a testing requirement and then
translated as necessary to other reference points.
[0033] As discussed herein, testing of the transceiver devices 305
for compliance with the core requirement does not necessarily have
to be done at the same reference point as the reference point at
which the requirement is defined. In other words, the conformance
test specification may define more than one reference point where
the requirement may be tested. How the test requirement at these
reference points is derived from the core requirement may be
described in the test specification. This procedure can take into
account the parameters declared by the manufacturer. Note that if
the requirement can be tested at multiple points there may be
multiple methods for deriving test requirements. For demonstrating
conformance it is sufficient to perform the test at one of the
described test points and then translate to the reference point
defined in these tests specification, as described herein.
[0034] In some embodiments, requirements defined at the antenna
connection point or in the far-field may be equivalent so that the
antenna connection requirement can be translated or mapped to the
far field requirements and vice versa. For example, for the
transmitter spurious emission requirement, the antenna connection
and far field requirements can be approximated by:
FarField-Req.apprxeq.r*AntConnector-Req+(1-r)*AntConnector-Req2,
where AntConnector-Req2 is the antenna connection-based requirement
that applies when the active antenna array 325 consists of a single
element 320. The parameter r indicates the degree of correlation
between the signals transmitted by the different elements 320. When
r approaches 1.0, the far field requirement would be the same as
antenna connection requirement. When r approaches 0.0, the far
field requirement would be the same as an active antenna array 325
that includes a single antenna element 320. In some embodiments,
the values of the parameter r may be determined by the equipment
specifications, beamforming weights, phases, or other parameters
used to transmit signals from the elements 320. Persons of ordinary
skill in the art having benefit of the present disclosure should
appreciate that alternative embodiments may use different
relationships to translate between the testing requirements at
different reference points. These relationships may be determined
experimentally, empirically, theoretically, using models, or other
techniques or combinations of these techniques.
[0035] FIG. 4 conceptually illustrates one exemplary embodiment of
a compliance tester 400. Some embodiments of the compliance tester
400 may be used as the antenna connection tester 230 shown in FIG.
2 or the far-field testers 340, 350 shown in FIGS. 3A-3B. In the
illustrated embodiment, the compliance tester 400 includes a
reference point mapping table 405. Some embodiments of the
reference point mapping table 405 may be used to relate testing
requirements at different reference points based upon a value of a
correlation parameter associated with the active antenna array
under test. For example, the reference point mapping table 405 may
be used to relate the testing requirements at an antenna connection
reference point and a field reference point using a relationship
that is determined based on the correlation parameter associated
with antenna elements in an active antenna array, as discussed
herein.
[0036] The compliance tester 400 shown in FIG. 4 also includes a
translator 410. The translator 410 may receive (at node 411)
information indicative of a value of a testing requirement that is
derived based on measurements performed at a first reference point,
such as measurements performed at a far-field reference point. The
translator may also receive (at node 412) information indicative of
a testing requirement defined for the test, such as a threshold
value of 45 dBc for an ACLR at an antenna connection reference
point. Alternatively, the compliance tester 400 may have the
information indicative of the testing requirements defined for the
test stored internally, e.g., in RAM, SRAM, or DRAM. The translator
410 may be configured to translate the testing requirements at one
or more of the reference points to values that correspond to other
reference points. For example, the translator 410 may translate the
values of the testing requirement determined based on measurements
at the far field reference point to values that correspond to the
testing requirement at the antenna connection reference point.
Alternatively, the translator 410 may translate a threshold value
of a testing requirement at the antenna connection reference points
to corresponding values at the far-field reference point.
[0037] The translated values can be provided to a comparator 415
implemented in the compliance tester 400. Since the translator 410
has translated the values of the testing requirements to a common
reference point, the comparator 415 can directly compare the
translated values received from the translator 410. For example,
the comparator 415 may determine whether the device under test
satisfies the compliance requirements by achieving an ACLR at the
far-field reference point that corresponds to a threshold value of
45 dBc for an ACLR at an antenna connection reference point.
[0038] FIG. 5 conceptually illustrates one exemplary embodiment of
a method 500 for translating test requirements for active antenna
arrays between different reference points. Some embodiments of the
method 500 may be implemented in a test apparatus such as the
testers 340, 350, 400 shown in FIGS. 3A, 3B, and 4. In the
illustrated embodiment, the tester accesses (at 505) one or more
requirements associated with a first reference point, such as an
antenna connection point or a far-field reference point. The tester
or another sensor that is physically, electromagnetically, or
communicatively coupled to the tester performs (at 510)
measurements at a second reference point that can be used to derive
(at 515) values of the testing requirements. However, as discussed
herein, the values derived (at 515) based on the measurements at
the second reference point may not be directly comparable to values
specified at the first reference point.
[0039] The tester may therefore translate (at 520) the testing
requirements for the second reference point to values that
correspond to the first reference point, e.g., using a mapping
table that maps values at the second reference point to the first
reference point based in part on correlation values associated with
the active antenna array. The tester may then compare (at 530) the
translated value to the values of the test requirements at the
first reference point. The comparison may be used to determine
whether the device under test complies with the testing
requirements that are defined for the first reference point. The
translated test requirements may also be used to compare test
results for different devices under test because the translated
test requirements refer to a common reference point, e.g. the first
reference point.
[0040] Portions of the disclosed subject matter and corresponding
detailed description are presented in terms of software, or
algorithms and symbolic representations of operations on data bits
within a computer memory. These descriptions and representations
are the ones by which those of ordinary skill in the art
effectively convey the substance of their work to others of
ordinary skill in the art. An algorithm, as the term is used here,
and as it is used generally, is conceived to be a self-consistent
sequence of steps leading to a desired result. The steps are those
requiring physical manipulations of physical quantities. Usually,
though not necessarily, these quantities take the form of optical,
electrical, or magnetic signals capable of being stored,
transferred, combined, compared, and otherwise manipulated. It has
proven convenient at times, principally for reasons of common
usage, to refer to these signals as bits, values, elements,
symbols, characters, terms, numbers, or the like.
[0041] It should be borne in mind, however, that all of these and
similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these
quantities. Unless specifically stated otherwise, or as is apparent
from the discussion, terms such as "processing" or "computing" or
"calculating" or "determining" or "displaying" or the like, refer
to the action and processes of a computer system, or similar
electronic computing device, that manipulates and transforms data
represented as physical, electronic quantities within the computer
system's registers and memories into other data similarly
represented as physical quantities within the computer system
memories or registers or other such information storage,
transmission or display devices.
[0042] Note also that the software implemented aspects of the
disclosed subject matter are typically encoded on some form of
program storage medium or implemented over some type of
transmission medium. The program storage medium may be magnetic
(e.g., a floppy disk or a hard drive) or optical (e.g., a compact
disk read only memory, or "CD ROM"), and may be read only or random
access. Similarly, the transmission medium may be twisted wire
pairs, coaxial cable, optical fiber, or some other suitable
transmission medium known to the art. The disclosed subject matter
is not limited by these aspects of any given implementation.
[0043] Furthermore, the methods disclosed herein may be governed by
instructions that are stored in a non-transitory computer readable
storage medium and that are executed by at least one processor of a
computer system. Each of the operations of the methods may
correspond to instructions stored in a non-transitory computer
memory or computer readable storage medium. In various embodiments,
the non-transitory computer readable storage medium includes a
magnetic or optical disk storage device, solid state storage
devices such as Flash memory, or other non-volatile memory device
or devices. The computer readable instructions stored on the
non-transitory computer readable storage medium may be in source
code, assembly language code, object code, or other instruction
format that is interpreted and/or executable by one or more
processors.
[0044] The particular embodiments disclosed above are illustrative
only, as the disclosed subject matter may be modified and practiced
in different but equivalent manners apparent to those skilled in
the art having the benefit of the teachings herein. Furthermore, no
limitations are intended to the details of construction or design
herein shown, other than as described in the claims below. It is
therefore evident that the particular embodiments disclosed above
may be altered or modified and all such variations are considered
within the scope of the disclosed subject matter. Accordingly, the
protection sought herein is as set forth in the claims below.
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